Commit 31eae6d9 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

selftests: drv-net: test drivers sleeping in ndo_get_stats64 



Most of our tests use rtnetlink to read device stats, so they
don't expose the drivers much to paths in which device stats
are read under RCU. Add tests which hammer profcs reads to
make sure drivers:
 - don't sleep while reporting stats,
 - can handle parallel reads,
 - can handle device going down while reading.

Set ifname on the env class in NetDrvEnv, we already do that
in NetDrvEpEnv.

  KTAP version 1
  1..7
  ok 1 stats.check_pause
  ok 2 stats.check_fec
  ok 3 stats.pkt_byte_sum
  ok 4 stats.qstat_by_ifindex
  ok 5 stats.check_down
  ok 6 stats.procfs_hammer
  # completed up/down cycles: 6
  ok 7 stats.procfs_downup_hammer
  # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0

Reviewed-by: default avatarPetr Machata <petrm@nvidia.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250107022932.2087744-1-kuba@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 7bf1659b

tools/testing/selftests/drivers/net/lib/py/env.py

+1 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ class NetDrvEnv: 
        else:

            self._ns = NetdevSimDev(**kwargs)

            self.dev = self._ns.nsims[0].dev

        self.ifname = self.dev['ifname']

        self.ifindex = self.dev['ifindex']



    def __enter__(self):

tools/testing/selftests/drivers/net/stats.py

+91 −3
Original line number Diff line number Diff line
@@ -2,12 +2,15 @@ 
# SPDX-License-Identifier: GPL-2.0



import errno

import subprocess

import time

from lib.py import ksft_run, ksft_exit, ksft_pr

from lib.py import ksft_ge, ksft_eq, ksft_in, ksft_true, ksft_raises, KsftSkipEx, KsftXfailEx

from lib.py import ksft_ge, ksft_eq, ksft_is, ksft_in, ksft_lt, ksft_true, ksft_raises

from lib.py import KsftSkipEx, KsftXfailEx

from lib.py import ksft_disruptive

from lib.py import EthtoolFamily, NetdevFamily, RtnlFamily, NlError

from lib.py import NetDrvEnv

from lib.py import ip, defer

from lib.py import cmd, ip, defer



ethnl = EthtoolFamily()

netfam = NetdevFamily()
@@ -174,10 +177,95 @@ def check_down(cfg) -> None: 
    netfam.qstats_get({"ifindex": cfg.ifindex, "scope": "queue"}, dump=True)





def __run_inf_loop(body):

    body = body.strip()

    if body[-1] != ';':

        body += ';'



    return subprocess.Popen(f"while true; do {body} done", shell=True,

                            stdout=subprocess.PIPE, stderr=subprocess.PIPE)





def __stats_increase_sanely(old, new) -> None:

    for k in old.keys():

        ksft_ge(new[k], old[k])

        ksft_lt(new[k] - old[k], 1 << 31, comment="likely wrapping error")





def procfs_hammer(cfg) -> None:

    """

    Reading stats via procfs only holds the RCU lock, which is not an exclusive

    lock, make sure drivers can handle parallel reads of stats.

    """

    one = __run_inf_loop("cat /proc/net/dev")

    defer(one.kill)

    two = __run_inf_loop("cat /proc/net/dev")

    defer(two.kill)



    time.sleep(1)

    # Make sure the processes are running

    ksft_is(one.poll(), None)

    ksft_is(two.poll(), None)



    rtstat1 = rtnl.getlink({"ifi-index": cfg.ifindex})['stats64']

    time.sleep(2)

    rtstat2 = rtnl.getlink({"ifi-index": cfg.ifindex})['stats64']

    __stats_increase_sanely(rtstat1, rtstat2)

    # defers will kill the loops





@ksft_disruptive

def procfs_downup_hammer(cfg) -> None:

    """

    Reading stats via procfs only holds the RCU lock, drivers often try

    to sleep when reading the stats, or don't protect against races.

    """

    # Max out the queues, we'll flip between max and 1

    channels = ethnl.channels_get({'header': {'dev-index': cfg.ifindex}})

    if channels['combined-count'] == 0:

        rx_type = 'rx'

    else:

        rx_type = 'combined'

    cur_queue_cnt = channels[f'{rx_type}-count']

    max_queue_cnt = channels[f'{rx_type}-max']



    cmd(f"ethtool -L {cfg.ifname} {rx_type} {max_queue_cnt}")

    defer(cmd, f"ethtool -L {cfg.ifname} {rx_type} {cur_queue_cnt}")



    # Real test stats

    stats = __run_inf_loop("cat /proc/net/dev")

    defer(stats.kill)



    ipset = f"ip link set dev {cfg.ifname}"

    defer(ip, f"link set dev {cfg.ifname} up")

    # The "echo -n 1" lets us count iterations below

    updown = f"{ipset} down; sleep 0.05; {ipset} up; sleep 0.05; " + \

             f"ethtool -L {cfg.ifname} {rx_type} 1; " + \

             f"ethtool -L {cfg.ifname} {rx_type} {max_queue_cnt}; " + \

              "echo -n 1"

    updown = __run_inf_loop(updown)

    kill_updown = defer(updown.kill)



    time.sleep(1)

    # Make sure the processes are running

    ksft_is(stats.poll(), None)

    ksft_is(updown.poll(), None)



    rtstat1 = rtnl.getlink({"ifi-index": cfg.ifindex})['stats64']

    # We're looking for crashes, give it extra time

    time.sleep(9)

    rtstat2 = rtnl.getlink({"ifi-index": cfg.ifindex})['stats64']

    __stats_increase_sanely(rtstat1, rtstat2)



    kill_updown.exec()

    stdout, _ = updown.communicate(timeout=5)

    ksft_pr("completed up/down cycles:", len(stdout.decode('utf-8')))





def main() -> None:

    with NetDrvEnv(__file__, queue_count=100) as cfg:

        ksft_run([check_pause, check_fec, pkt_byte_sum, qstat_by_ifindex,

                  check_down],

                  check_down, procfs_hammer, procfs_downup_hammer],

                 args=(cfg, ))

    ksft_exit()

tools/testing/selftests/net/lib/py/ksft.py

+5 −0
Original line number Diff line number Diff line
@@ -71,6 +71,11 @@ def ksft_in(a, b, comment=""): 
        _fail("Check failed", a, "not in", b, comment)





def ksft_is(a, b, comment=""):

    if a is not b:

        _fail("Check failed", a, "is not", b, comment)





def ksft_ge(a, b, comment=""):

    if a < b:

        _fail("Check failed", a, "<", b, comment)